Can common forest bird species tolerate disturbances in neighbouring areas? A case study of the Vuosaari Harbour construction in southern Finland

Urbanization and other human activities can lead to decreasing animal populations in nearby areas. The impact of human activitiesmay vary depending on the characteristics of the areas and region or on the strength of the disturbance. We investigated forest bird population changes in an EU Natura 2000 area during the construction of the new Helsinki Vuosaari Harbour in southern Finland in 2002-2011 as part of an environmental impact assessment. We evaluated whether the changes observed were linked with the harbour construction work by comparing the populations at sites near the development with those corresponding values obtained from national common bird monitoring in southern Finland. Themean population changes of 23 boreal forest bird species that inhabited the Natura 2000 area and southern Finland were significantly and positively correlated, but the population inside the Natura 2000 study area also showed lower mean numbers (a mean decline of 9% occurred over the study period). Our case study emphasizes the importance of intensive monitoring before, during and after work at the construction site and in the surrounding areas to detect actual changes in the populations.Peer reviewe